Glass etching
The wonders of Glass Etching explained, with photos of acid etching glass
What is Glass Etching?
Glass etching is a process by which a resist is applied to glass before it is dipped into hydrofluoric acid where the exposed surface is eaten away.
What etching supplies do you need?
- Glass (flashed or streaky if colour differentiation wanted)
- Sticky-backed plastic
- Resist (wax, fablon or bitumen)
- raft knife
- Hydrofluoric acid – diluted 3:1
- Dibbler or feather
- Apron
- Latex and rubber gloves
You can also buy etching kits which use paste and contain many of the materials you need already included. The best value glass etching kit is definitely the Armour Deluxe Glass Etching Kit
Identifying flashed (coloured) side
Seedy glass – bubbles will be coloured on the flashed side and clear on the white side.
If there are no bubbles you can cut a small triangle off the edge of the glass and visually identify which side the layer of colour (flash) is on.
Mark the flashed side to prevent glass etching on the wrong side.
Masking up
Put fablon on the back of the glass to protect the reverse side of the glass. Cut a piece of fablon slightly larger than the glass, take the backing off and place the glass on it. Squeeze out any bubbles and finally cut around the edges with a craft knife.
Stopping out – resists
Resists are put on the glass and left to dry before immersing glass in diluted hydrofluoric acid. Put resist on where you want colour to remain.
Choose the resist/s to suit the effect you want to create:
Fablon – creates very sharp shapes. Very precise and linear.
Bitumen – creates very painterly effects. Can be sponged, stippled or painted on. Can be scratched into just before drying. Can be used as a silkscreen resist and for ‘marbling’. This is done by floating the bitumen on water and, before it hardens, placing the glass on top of the random pattern.
Wax – creates softer, freer lines. Wax allows the acid to creep under edges, giving a softer etch than bitumen. Can be scratched into. Wax dries on contact with the glass, so you need to work quickly to avoid blobby messes!
Best ratios of wax = one-third beeswax, one-third tallow and one-third paraffin wax.
This mix allows smoother application of wax and melts at a low temperature. Melt the wax in a thermostatically controlled container, making sure that the brushes are also warmed up. Beware! – wax can float off in cold weather and if it has not been applied when sufficiently hot.
Mopping
The process by which shaded edges are achieved. Make a dibbler by wrapping some cotton wool in a piece of nappy lining and tie to the end of a bamboo stick. Dip the dibbler into very strong or neat acid, and stroke the area of glass that requires shading repeatedly, until the flash is removed to your liking.
Glass etching and abrading
This process produces a contrast of clear and opaque glass. It is useful for textural interest and for providing levels of obscurity to float glass. You can use any resist, with the proviso that the glass etching is quite deep, otherwise the process of abrading will flatten out the whole surface of the glass and rub out your textural effects.
Once you have etched the glass, clean off the resist and, using a smaller piece of glass, water and an abrasive powder, rub evenly across the surface of the etched glass. The choice of abrading powder determines the quality of the abraded surface – the coarser it is the coarser the abrade will be. Carborundum powder, bauxlite abrading powder or silicon carbide can be used.
Acid paste
This technique produces subtle opaque areas of glass and is best used on clear or lightly coloured glass. Wear latex gloves and apply the paste with anything that gives you the texture you desire. Leave undisturbed for 20 minutes and wash the paste off under running water. Dry thoroughly. Acid paste can also be used for screen-printing.
Health and Safety -This can be a very dangerous technique so safety is very important. Always wear protective gloves and goggles and work in a well ventilated space with running water at hand. Do not attempt this away from a properly equipped studio with supervision if you are unsure what you are doing.
